Process and apparatus for electronic control of the transfer and delivery of high purity chemicals

• US 5,330,072 A
• Filed: 09/21/1992
• Issued: 07/19/1994
• Est. Priority Date: 09/17/1990
• Status: Expired due to Term

• Current Assignee: Air Liquide Electronics US LP (Air Liquide SA)
• Original Assignee: Applied Chemical Solutions, Inc. (Tokyo Electron Limited)
• Inventors: Geatz, J. Tobin, Ferri, Edward T. Jr.
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): Bomberg, Kenneth
• Application Number:
  US07/948,392
• Time in Patent Office: 666 Days
• Field of Search: 137/205, 137/208, 137/209, 137/545, 222/1, 222/43, 222/56, 222/135, 222/152, 222/309, 222/318, 222/399, 222/59, 222/61, 222/71
• US Class Current: 222/1
• CPC Class Codes: B01F 2101/2204 Mixing chemical components in generals in order to improve chemical treatment or reactions, independently from the specific application
• CPC Class Codes: B01F 35/2217 Volume of at least one component to be mixed
• CPC Class Codes: B01F 35/882 using measuring chambers, e.g. volumetric pumps, for feeding the substances
• CPC Class Codes: B24B 37/04 designed for working plane surfaces
• CPC Class Codes: B67D 7/0272 specially adapted for transferring liquids of high purity
• CPC Class Codes: B67D 7/0283 specially adapted for transferring liquids of high purity
• CPC Class Codes: G01F 11/28 with stationary measuring chambers having constant volume during measurement
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/67276 Production flow monitoring, e.g. for increasing throughput program-control systems per se G05B19/00, e.g. total factory control G05B19/418
• CPC Class Codes: Y10T 137/3109 Liquid filling by evacuating container
• CPC Class Codes: Y10T 137/3124 Plural units
• CPC Class Codes: Y10T 137/3127 With gas maintenance or application

Abstract

The present invention provides improved method and apparatus for the transfer and delivery of very high purity chemicals for use in semiconductor production and similar processes. By employing a series of vessels arranged in parallel, a vacuum system to draw chemical from one or more bulk sources into the vessels, and a pressure system to deliver chemical under pressure from the vessels, chemicals can be easily delivered from any bulk source to one or more end-users. The use of a vacuum system to draw chemicals through sealed conduits eliminates the need for pumps which are a source of both maintenance problems and contamination in the system. Multiple vessels provide for a variety of flow options, which include continuous and uniform chemical delivery to the end-users, recirculation and regular filtration during periods of low use, and built-in redundancy to avoid system shut down if there is a component failure. Computer controlled process systems provides system flexibility and full automation.

Claims

1. A process for control of apparatus for transfer and delivery of chemical from at least one bulk source to at least one end-use station which comprises:

providing multiple vessels, each such vessel including valving to control flow of chemical into and out of the vessel;

providing at least one conduit for the flow of chemical between the bulk source and each such vessel;

providing at least one conduit for the flow of chemical between each such vessel and an end-use station;

providing means to transfer chemical at a uniform flow rate from a bulk source to each such vessel;

providing means to pressurize each such vessel, including valving to control the flow of pressurized gas into each vessel;

providing means to sense level of chemical in each such vessel and to provide a signal therefor;

providing means to sense demand for chemical at an end-use station and to provide a signal therefor;

providing electronic means to analyze the signals from each of the means to sense the presence of chemical in each vessel and the means to sense demand at an end-use station and to regulate the operation of the valving in response thereto;

controlling chemical flow through each vessel through the steps comprising;

when low chemical level is sensed in a vessel, the electronic means regulates the valving so as to cause chemical to be transferred from a bulk source into the vessel until a high chemical level is sensed;

when a high chemical level is sensed in a vessel, the electronic means regulates the valving so as to cause the vessel to be pressurized; and

when a demand is sensed at an end-use station, the electronic means regulates the valving to cause chemical to be delivered under pressure from the vessel to the end-use station; and

maintaining uniform flow rate of chemical through the system through the steps comprising;

when a low chemical level is sensed in a first vessel delivering chemical, the electronic means regulates the valving to cause chemical to be delivered from a second vessel before the first vessel is completely evacuated, so as to assure no interruption in flow.

2. The process of claim 1 which further comprises providing at least one conduit for the flow of chemical between each such vessel and the bulk source;

and

wherein when chemical has been contained in a vessel for a predetermined period of time without demand from an end-use station, the electronic means regulates the valving to cause the chemical to be recirculated to the bulk source.

3. The process of claim 1 wherein said means to transfer chemical at a uniform flow rate from a bulk source to each such vessel comprises

providing means to decompress each such vessel, including valving to control the flow of gas from each vessel;

and

wherein chemical is transferred from the bulk source to each vessel by decompressing the vessel so as to form a vacuum therein and regulating the valving of the vessel so as to cause chemical to be drawn through the conduit between the bulk source and the vessel motivated by the pressure differential between the decompressed vessel and the bulk source.

4. The process of claim 1 including providing means responsive to the electronic means to convey information to an operator concerning the status of selected operational criteria of the apparatus.

5. The process of claim 4 wherein said means to provide information to an operator includes providing a visual display identifying the status of the operational criteria.

6. The process of claim 1 including supplying continuous chemical delivery by:

immediately refilling the first vessel once the second vessel is delivering chemical to the end-use station; and

when low chemical level is sensed in the second vessel delivering chemical, the electronic means regulates the valving to cause chemical to be delivered from the first vessel before the second vessel is completely evacuated.

7. The process of claim 6 including increasing capacity of the system by providing at least one additional vessel which may be alternatively filled and evacuated in conjunction with the first and second vessels.

8. The process of claim 7 including maintaining system operation in an instance where a component of one of the vessels fails to function by employing the electronic means to regulate the valving so that chemical flow is diverted around the vessel with a failed component.

9. The process of claim 1 including providing means, in fluid communication with a conduit in the system, to filter the chemical, and filtering the chemical to improve its purity.

10. The process of claim 2 including providing means, in fluid communication with a conduit in the system, to filter the chemical, and filtering the chemical to improve its purity when it is recirculated.

11. The process of claim 2 including maintaining at least one vessel filled and pressurized to deliver chemical to an end-use station upon demand while chemical from any of the other vessels is being recirculated.

12. The process of claim 11 including periodically alternating the vessel which is filled and pressurized to deliver chemical upon demand so as to assure a homogenous mixture of chemical throughout the system.

13. The process of claim 1 wherein said means to transfer chemical at a uniform flow rate from a bulk source to each such vessel comprises

providing the bulk source at an elevation above that of the vessels so as to create a pressure differential between the bulk source and the vessels;

and

wherein chemical is transferred from the bulk source to each vessel by regulating the valving of the vessel so as to cause chemical to be driven through the conduit between the bulk source and the vessel motivated by the pressure differential between the vessel and the bulk source.